The present invention relates generally to proximity detection systems, and more particularly to a capacitive proximity detection system for an appliance such as a refrigerator.
Capacitive proximity sensors and systems rely on electrostatic fields that are disturbed. When an object passes the sensing face of the capacitive proximity sensor, the electric field is disturbed and provides an output signal. Physical contact with the object is not required and any type of object can be detected, without regard to material or conductivity.
Although devices employing capacitive proximity sensors are known, the application of capacitive proximity sensors in refrigerators is problematic because the refrigerator is typically a large, grounded metal object. The large size of refrigerators, and the corresponding ground plane affects capacitive proximity detection since the ground plane absorbs the electrostatic field. This diminishes the range of proximity detection systems in refrigerators. It would be advantageous to be able to reduce the influence of the ground plane of a refrigerator in a proximity detection system for an appliance. It would also be advantageous to enhance the range of proximity sensing in a refrigerator.